Many insecticides have bee developed and used for the purposes of preventing and keeping off various insanitary or unpleasant, harmful insects. When application of insecticides is difficult or undesirable, however, repellents are used. Although many repellents are also known already, there are some problems about their effects and other respects and only a few of them are used practically. For instance, N,N-diethyl-m-toluamide (hereinafter abbreviated as Deet) described in U.S. Pat. No. 2,932,665 is already used practically as a repellent. However, its effect disappears within a relatively short period of time and the effect also is not always satisfactory. On the other hand, O-alkyl-N-phenylthiocarbamates are disclosed in German Pat. No. 1,139,694 to have a miticidal effect, but no description is given therein as regards their repellent effect. According to the knowledge of the present inventors, however, these O-alkyl-N-phenylthiocarbamates disclosed in the above-mentioned German patent have an unexpected property of showing an excellent repellent effect against insects, ticks and mites, although their insecticidal and miticidal effect is too weak to use them practically as an insecticide or miticide.
Thus, the present inventors have made various investigations for further improving the repellent effect of the O-alkyl-N-phenylthiocarbamates, particularly with the purposes of developing a repellent having an immediate and durable effect, and found that O-alkyl-N-phenylthiocarbamates having an alkyl group of the small number of carbon atoms have a relatively strong repellent effect and further that, by mixing such thiocarbamates with Deet, a superior effect to that which may be produced by adding the effects of the individual components can be obtained.